Nrf2: A promising therapeutic target in bone-related diseases

Allicin attenuates the oxidative damage induced by Aflatoxin B1 in dairy cow hepatocytes via the Nrf2 signalling pathway

Aflatoxin B1 (AFB1) is known to inhibit growth, and inflict hepatic damage by interfering with protein synthesis. Allicin, has been acknowledged as an efficacious antioxidant capable of shielding the liver from oxidative harm. This study aimed to examine the damage caused by AFB1 on bovine hepatic cells and the protective role of allicin against AFB1-induced cytotoxicity. In this study, cells were pretreated with allicin before the addition of AFB1 for co-cultivation. Our findings indicate that AFB1 compromises cellular integrity, suppresses the expression of nuclear factor erythroid 2-related factor 2 (Nrf2). In addition, allicin attenuates oxidative damage to bovine hepatic cells caused by AFB1 by promoting the expression of the Nrf2 pathway and reducing cell apoptosis. In conclusion, the results of this study will help advance clinical research and applications, providing new options and directions for the prevention and treatment of liver diseases.

Protopine protects chondrocytes from undergoing ferroptosis by activating Nrf2 pathway

Osteoarthritis is a highly prevalent joint disease; however, effective treatments are lacking. Protopine (PTP) is an isoquinoline alkaloid with potent anti-inflammatory and antioxidant properties; however, it has not been studied in osteoarthritis. This study aimed to investigate whether PTP can effectively protect chondrocytes from ferroptosis. Primary mouse chondrocytes were treated with tert-butyl hydroperoxide (TBHP) to simulate oxidative stress in an in vitro model of osteoarthritis. Two concentrations of PTP (10 and 20 μg/mL) were validated for in vitro experiments. Cellular inflammation and metabolism were detected using RT-qPCR and western blotting (WB). Ferroptosis was assessed via WB, qPCR, reactive oxygen species (ROS) levels, lipid ROS, and immunofluorescence staining. In vitro, PTP significantly ameliorated chondrocyte inflammation and cytolytic metabolism and significantly suppressed chondrocyte ferroptosis through the activation of the Nrf2 pathway. The anterior cruciate ligament transection (ACLT) mouse model was used to validate the in vivo effects of PTP. The joint cartilage was assessed using the Osteoarthritis Research Society International (OARSI) score, Safranin O staining, and immunohistochemistry. The intra-articular administration of PTP alleviated cartilage inflammation and ferroptosis, as evidenced by the expression of MMP3, MMP13, COL2A1, GPX4, and Nrf2. Overall, we find that PTP exerted anti-ferroptosis and anti-inflammatory effects on chondrocytes to protect the articular cartilage.

Glycogen Synthase Kinase-3 Beta (GSK3β) as a Potential Drug Target in Regulating Osteoclastogenesis: An Updated Review on Current Evidence

Glycogen synthase kinase 3-beta (GSK3β) is a highly conserved protein kinase originally involved in glucose metabolism, insulin activity, and energy homeostasis. Recent scientific evidence demonstrated the significant role of GSK3β in regulating bone remodelling through involvement in multiple signalling networks. Specifically, the inhibition of GSK3β enhances the conversion of osteoclast progenitors into mature osteoclasts. GSK3β is recognised as a pivotal regulator for the receptor activator of nuclear factor-kappa B (RANK)/receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG), phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT), nuclear factor-kappa B (NF-κB), nuclear factor-erythroid 2-related factor 2 (NRF2)/Kelch-like ECH-associated protein 1 (KEAP1), canonical Wnt/beta (β)-catenin, and protein kinase C (PKC) signalling pathways during osteoclastogenesis. Conversely, the inhibition of GSK3β has been shown to prevent bone loss in animal models with complex physiology, suggesting that the role of GSK3β may be more significant in bone formation than bone resorption. Divergent findings have been reported regarding the efficacy of GSK3β inhibitors as bone-protecting agents. Some studies demonstrated that GSK3β inhibitors reduced osteoclast formation, while one study indicated an increase in osteoclast formation in RANKL-stimulated bone marrow macrophages (BMMs). Given the discrepancies observed in the accumulated evidence, further research is warranted, particularly regarding the use of GSK3β silencing or overexpression models. Such efforts will provide valuable insights into the direct impact of GSK3β on osteoclastogenesis and bone resorption.

The Therapeutic Potential of Two Egyptian Plant Extracts for Mitigating Dexamethasone-Induced Osteoporosis in Rats: Nrf2/HO-1 and RANK/RANKL/OPG Signals

The prolonged use of exogenous glucocorticoids, such as dexamethasone (Dex), is the most prevalent secondary cause of osteoporosis, known as glucocorticoid-induced osteoporosis (GIO). The current study examined the preventative and synergistic effect of aqueous chicory extract (ACE) and ethanolic purslane extract (EPE) on GIO compared with Alendronate (ALN). The phytochemical contents, elemental analysis, antioxidant scavenging activity, and ACE and EPE combination index were evaluated. Rats were randomly divided into control, ACE, EPE, and ACE/EPE MIX groups (100 mg/kg orally), Dex group (received 1.5 mg Dex/kg, Sc), and four treated groups received ACE, EPE, ACE/EPE MIX, and ALN with Dex. The bone mineral density and content, bone index, growth, turnover, and oxidative stress were measured. The molecular analysis of RANK/RANKL/OPG and Nrf2/HO-1 pathways were also evaluated. Dex causes osteoporosis by increasing oxidative stress, decreasing antioxidant markers, reducing bone growth markers (OPG and OCN), and increasing bone turnover and resorption markers (NFATc1, RANKL, ACP, ALP, IL-6, and TNF-α). In contrast, ACE, EPE, and ACE/EPE MIX showed a prophylactic effect against Dex-induced osteoporosis by modulating the measured parameters and the histopathological architecture. In conclusion, ACE/EPE MIX exerts a powerful synergistic effect against GIO by a mode of action different from ALN.